Bridge arm detection protection circuit and H-type bridge circuit using same

Abstract

The invention discloses a bridge arm detection protection circuit and an H-type bridge circuit using the same, and the bridge arm detection protection circuit comprises a current sampling module which is used for carrying out the current sampling of any pair of diagonal switching tubes in the H-type bridge circuit; the differential amplification module is electrically connected to the current sampling module and is used for carrying out differential amplification on the sampling signal; and the full-wave rectification module is electrically connected to the differential amplification module and is used for obtaining an absolute value of the amplified signal. According to the invention, the bridge arm straight-through event of the H-type bridge circuit can be detected more sensitively and quickly, and the bridge arm straight-through monitoring effect under various conditions can be met.

Description

Technical Field

[0001] The present application relates to the field of power conversion technology, and in particular to a bridge arm detection protection circuit and an H-type bridge circuit using the same. Background Art

[0002] H-bridge circuits are commonly used in power conversion applications, such as single-phase inverters and DC / DC converters. However, H-bridge circuits have the risk of direct conduction between the upper and lower switches in the same arm, leading to low conversion efficiency and component heating. In severe cases, they can even damage the power switches and other components.

[0003] At present, in the power electronic products on the market, the shoot-through detection and protection of H-type bridge arms mainly rely on the following three methods: overcurrent protection, direct protection of short-circuited components through driver chip DESAT protection, and drive interlock / monitoring circuit to prevent the same bridge arm switch tube from being driven at a high level at the same time to prevent shoot-through.

[0004] Both overcurrent protection and the driver chip's DESAT protection require that the current climb to a certain value greater than that during normal operation after a bridge arm shoot-through event occurs before they can be triggered. In addition, DESAT detection has a leading-edge blanking time problem. Overall, these two methods have slow response speeds and low sensitivity, and cannot effectively respond to some short-term bridge arm shoot-throughs where the shoot-through current has not climbed to trigger overcurrent or DESAT.

[0005] However, the driver interlock cannot effectively respond to the drive transmission delay caused by the aging of the driver optocoupler and the shoot-through caused by the turn-off delay of the switching device itself. In addition, the driver interlock / monitoring cannot provide effective protection signals to other devices when a short-circuit fault occurs due to the failure of an existing switching tube device. Summary of the Invention

[0006] In order to detect the H-type bridge circuit arm straight-through event more sensitively and quickly and meet the bridge arm straight-through monitoring under various conditions, the present application provides a bridge arm detection protection circuit and an H-type bridge circuit using the same.

[0007] In a first aspect, the present application provides a bridge arm detection protection circuit, which adopts the following technical solution:

[0008] A bridge arm detection protection circuit, comprising:

[0009] A current sampling module is used to sample the current of any pair of diagonal switches in an H-bridge circuit;

[0010] a differential amplification module, electrically connected to the current sampling module, for performing differential amplification on the sampling signal; and

[0011] The full-wave rectifier module is electrically connected to the differential amplifier module and is used to obtain the absolute value of the amplified signal.

[0012] Optionally, the current sampling module includes:

[0013] Two current mutual inductance coils, each with its primary winding connected in series to a diagonal switch tube of an H-bridge circuit, and one end of its secondary winding grounded; and

[0014] There are two sets of current sampling resistors, which are connected in parallel to the secondary windings of the two current mutual inductance coils;

[0015] The current mutual inductance coil is connected to the current sampling resistor and one end thereof that is not grounded is electrically connected to the differential amplification module.

[0016] Optionally, the differential amplification module includes:

[0017] Amplifier U1, whose non-inverting and inverting input terminals are electrically connected to two current sampling resistors respectively, and whose output terminal is connected to a full-wave rectifier module;

[0018] Resistor eight R8, connected in series to one input terminal of amplifier U1;

[0019] Resistor R10 is connected in series to the other input terminal of amplifier U1;

[0020] Resistor nine R11, one end of which is connected to the connection point of resistor ten R10 and amplifier U1, and the other end is connected to the full-wave rectifier module;

[0021] Resistor nine R9 has one end connected to the connection point between resistor eight R8 and amplifier U1, and the other end connected to the output terminal of amplifier U1.

[0022] Optionally, the full-wave rectifier module includes two diode combinations, the diode combination includes two diodes connected in series, the two diode combinations are in a parallel structure and the two ends of the parallel connection serve as signal output ends; one end of the resistor eleven R11 is connected between the two diodes connected in series, and the connection point between the output end of the amplifier U1 and the resistor nine R9 is connected between another group of two diodes connected in series.

[0023] Optionally, a resistor 12 R12 is further included, the connection point between the resistor 11 R11 and the full-wave rectifier module is connected to one end of the resistor 12 R12, and the other end of the resistor 12 R12 is grounded.

[0024] Optionally, a filter capacitor C1 is further included, and the filter capacitor C1 is connected in parallel to the output side of the full-wave rectifier module.

[0025] Optionally, a discharge resistor thirteen R13 is further included, and the discharge resistor thirteen R13 is arranged in parallel with the filter capacitor C1.

[0026] In a second aspect, the present application provides an H-bridge circuit, which adopts the following technical solution:

[0027] An H-type bridge circuit is provided, in which any of the above-mentioned bridge arm detection and protection circuits is applied.

[0028] In summary, the present application has at least one of the following beneficial technical effects: by sampling the currents of any pair of diagonal switch tubes in the H-bridge in equal proportion and performing differential amplification, and then taking the absolute value of the amplified signal through a full-wave rectifier module, this absolute value signal can effectively reflect the current difference between the diagonal switch tubes, thereby determining whether a full or short-term shoot-through occurs in the bridge arm;

[0029] Based on the above, 1. Because the present invention directly monitors the inherent phenomenon after bridge arm shoot-through occurs (the difference in diagonal switch tube current), it is suitable for monitoring bridge arm shoot-through in various situations in H-bridge circuits (including single-phase inverter / LLC full-bridge / hard-switching full-bridge) and providing effective protection signals. The monitoring / protection coverage is wider than existing solutions.

[0030] 2. Because the current difference of the diagonal switch tubes is always zero when the bridge arm does not directly conduct; as long as it is detected that the current difference of the diagonal switch tubes begins to rise after the bridge arm directly conducts, a protection signal can be given without waiting for the current to climb to trigger overcurrent protection or component DESAT protection. Therefore, it is more sensitive and faster than existing solutions.

[0031] 3. It can effectively monitor the periodic short-term bridge arm direct conduction during the operation of the H-bridge circuit, which can give circuit designers more confidence in the design and application process to try to shorten the switching dead time, thereby achieving higher conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the circuit structure of this application;

[0033] Figure 2 This is the H-bridge operating mode of the single-phase inverter circuit of the present application;

[0034] Figure 3 The voltage and current waveforms at both ends of the load of the single-phase inverter circuit of the present application are as follows;

[0035] Figure 4 yes Figure 1 The Vout waveform of the H-bridge circuit during normal operation;

[0036] Figure 5 yes Figure 1 The Vout waveform of the H-bridge circuit M1 / M2 bridge arm when it is directly connected for 3us per cycle. DETAILED DESCRIPTION

[0037] The following is combined with Figure 1-5 Request further details.

[0038] An embodiment of the present application discloses a bridge arm detection protection circuit.

[0039] Reference Figure 1 , the bridge arm detection protection circuit includes:

[0040] A current sampling module is used to sample the current of any pair of diagonal switches in an H-bridge circuit;

[0041] a differential amplification module, electrically connected to the current sampling module, for performing differential amplification on the sampling signal; and

[0042] The full-wave rectifier module is electrically connected to the differential amplifier module and is used to obtain the absolute value of the amplified signal.

[0043] The above-mentioned H-bridge circuit utilizes the characteristic that when the bridge arm shoot-through does not occur, the current of the diagonal switch tubes is always consistent during normal operation, but once the bridge arm shoot-through occurs, the current difference of the diagonal switch tubes will inevitably increase rapidly. By sampling the current of any pair of diagonal switch tubes in the H bridge in equal proportion and performing differential amplification, and then taking the absolute value of the amplified signal through full-wave rectification (or absolute value circuit), this absolute value signal can effectively reflect the current difference of the diagonal switch tubes, thereby determining whether the bridge arm has completely or briefly shoot-through.

[0044] The details are explained below.

[0045] The current sampling module includes:

[0046] There are two current mutual inductance coils, denoted as TX1 and TX2, and TX1 and TX2 are respectively connected in series with a diagonal switch tube of the H-bridge circuit through the primary winding, and one end of the secondary winding is grounded; and

[0047] There are two sets of current sampling resistors, denoted as resistor three R3 and resistor four R4, respectively. Resistor three R3 and resistor four R4 are connected in parallel to the secondary windings of the two current mutual inductance coils;

[0048] The current mutual inductance coil is connected to the current sampling resistor and one end thereof that is not grounded is electrically connected to the differential amplifier module.

[0049] The differential amplifier module includes:

[0050] Amplifier U1, whose non-inverting and inverting input terminals are electrically connected to two current sampling resistors respectively, and whose output terminal is connected to a full-wave rectifier module;

[0051] Resistor eight R8, connected in series to one input terminal of amplifier U1;

[0052] Resistor R10 is connected in series to the other input terminal of amplifier U1;

[0053] Resistor nine R11, one end of which is connected to the connection point of resistor ten R10 and amplifier U1, and the other end is connected to the full-wave rectifier module;

[0054] Resistor nine R9 has one end connected to the connection point between resistor eight R8 and amplifier U1, and the other end connected to the output terminal of amplifier U1.

[0055] According to the above settings, the differential op amp gain of amplifier U1 is determined by R8 / R9 / R10 / R11.

[0056] The full-wave rectifier module (U2) includes two diode combinations, each connected in series. The two diode combinations are connected in parallel, with their ends serving as the signal output terminals (OUT). One end of resistor R11 is connected between the two series diodes, and the junction between the output of amplifier U1 and resistor R9 is connected between another set of two series diodes.

[0057] According to the above settings, R8 / R9 / R10 / R11 serve as op amp proportional adjustment resistors.

[0058] In one embodiment of the present circuit, a resistor R12 is further included. The connection point between the resistor R11 and the full-wave rectifier module is connected to one end of the resistor R12, and the other end of the resistor R12 is grounded. In this case, the resistor R12 serves as a simulated ground isolation resistor.

[0059] In one embodiment of the present circuit, a filter capacitor C1 is further included. The filter capacitor C1 is connected in parallel to the output side of the full-wave rectifier module.

[0060] Furthermore, the circuit further includes a discharge resistor thirteen R13, and the discharge resistor thirteen R13 is arranged in parallel with the filter capacitor C1.

[0061] The above settings are used for filtering and discharging the output protection signal.

[0062] The embodiment of the present application also discloses an H-type bridge circuit.

[0063] Reference Figure 1 , H-type bridge circuit, in which the bridge arm detection protection circuit as described above is applied.

[0064] In the figure, V5 is the main circuit voltage source, and V1 / V3 / V6 / V7 are used to drive analog switch tubes. In actual applications, the switch tube drive will be provided by different control chips according to different circuit topologies. The four switch tubes M1 / M2 / M3 / M4 form an H-bridge circuit, and the resistor R2 and inductor L1 represent the load of the H-bridge.

[0065] For ease of understanding, when the H-bridge circuit works normally and no bridge arm shoot-through occurs, take a single-phase inverter circuit as an example:

[0066] See also Figure 2 , where M1 / M2 / M3 / M4 are equivalent to T1+D1 / T2+D2 / T3+D3 / T4+D4 respectively. At this time, the current flow direction and waveform under the four working modes of the circuit are as follows Figure 2 and Figure 3 shown.

[0067] Reference Figure 2 When the single-phase inverter H-bridge circuit is working normally, the switch states of M1 and M4 are consistent and the current is I M1 =I M4 , similarly I M2 =I M 3 (LLC full bridge and hard switch full bridge H bridge circuit is similar); at this time, the current collected by the secondary (secondary winding) of the current transformer coil is the same / similar (considering the transformer and resistor errors), that is, the voltage signal V collected by resistor three R3 and resistor four R4 R3 =I M3 / k*R3 and V R4 =I M2 / k*R4 is also equal, that is, V R3 -V R4 =0;

[0068] At this time, the output of amplifier U1 Vopout = a*(V R3 -V R4 ) = 0; the absolute value remains low, and the output absolute value Vout after full-wave rectification by U2 remains low;

[0069] When any of the bridge arms (such as M1 and M2 bridge arms) is directly connected,

[0070] According to Kirchhoff's current law, I M2 =I M3 +I M1 ;

[0071] At this time V R3 -V R4 = I M3 / k*R3-(I M3 +I M1 ) / k*R4 = -I M1 / k*R4;

[0072] The output of amplifier U1 is Vopout = a*(V R3 -V R4 ) = -a*I M1 / k*R4;

[0073] Vout=|Vopout|-VD = a*I M1 / k*R4 - VD, VD is the voltage drop of U2 full-wave rectifier circuit;

[0074] Since the bridge arms M1 and M2 are directly connected, the current will flow quickly to M1 and M2, and IM1 will rise rapidly in a very short time. At the same time, the op amp output Vopout will also drop rapidly toward the negative level, so that the absolute value of the protection signal Vout output by U2 after rectification is at a high level.

[0075] Reference Figure 4 , which is based on Figure 1 The simulation results show the Vout waveform when the H-bridge circuit is operating normally. When the H-bridge circuit is operating normally in switching mode, the monitoring signal Vout always maintains an extremely low level.

[0076] Reference Figure 5 , which is the Vout waveform when the H-bridge circuit M1 / M2 bridge arms are through-current for 3µs per cycle. When a short-term through-current fault occurs in one of the bridge arms, Vout climbs to a higher level in a short period of time.

[0077] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A bridge arm detection protection circuit, characterized in that: include: A current sampling module is used to sample the current of any pair of diagonal switches in an H-bridge circuit; a differential amplification module, electrically connected to the current sampling module, for performing differential amplification on the sampling signal; and The full-wave rectifier module is electrically connected to the differential amplifier module and is used to obtain the absolute value of the amplified signal.

2. The bridge arm detection protection circuit according to claim 1, characterized in that: The current sampling module includes: Two current mutual inductance coils, each with its primary winding connected in series to a diagonal switch tube of an H-bridge circuit, and one end of its secondary winding grounded; and There are two sets of current sampling resistors, which are connected in parallel to the secondary windings of the two current mutual inductance coils; The current mutual inductance coil is connected to the current sampling resistor and one end thereof that is not grounded is electrically connected to the differential amplification module.

3. The bridge arm detection protection circuit according to claim 1, characterized in that: The differential amplification module includes: Amplifier U1, whose non-inverting and inverting input terminals are electrically connected to two current sampling resistors respectively, and whose output terminal is connected to a full-wave rectifier module; Resistor eight R8, connected in series to one input terminal of amplifier U1; Resistor R10 is connected in series to the other input terminal of amplifier U1; Resistor nine R11, one end of which is connected to the connection point of resistor ten R10 and amplifier U1, and the other end is connected to the full-wave rectifier module; Resistor nine R9 has one end connected to the connection point between resistor eight R8 and amplifier U1, and the other end connected to the output terminal of amplifier U1.

4. The bridge arm detection protection circuit according to claim 1, characterized in that: The full-wave rectifier module includes two diode combinations, each of which includes two diodes connected in series. The two diode combinations are in a parallel structure, and the two ends of the parallel connection serve as signal output ends; one end of the resistor R11 is connected between the two diodes connected in series, and the connection point between the output end of the amplifier U1 and the resistor R9 is connected between another group of two diodes connected in series.

5. The bridge arm detection protection circuit according to claim 1, characterized in that: It also includes a resistor R12. The connection point between the resistor R11 and the full-wave rectifier module is connected to one end of the resistor R12, and the other end of the resistor R12 is grounded.

6. The bridge arm detection protection circuit according to claim 1, characterized in that: It also includes a filter capacitor C1, which is connected in parallel to the output side of the full-wave rectifier module.

7. The bridge arm detection protection circuit according to claim 6, characterized in that: The device further includes a discharge resistor thirteen R13 , which is connected in parallel with the filter capacitor C1 .

8. An H-bridge circuit, characterized in that: The bridge arm detection protection circuit as described in any one of claims 1 to 7 is applied to an H-bridge circuit.

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